It has been the practice in the past to provide planar magnetron sputtering targets within the sputtering chamber and to replace the depleted targets through an opening formed in the top of the chamber. The planar magnetrons have their horizontal, longitudinal axis extending crosswise of the vacuum chamber through which the substrate will be passed. In this manner, the substrates being sputter coated, such as architectural panels of relatively large size, can be enclosed in the chamber and are passed beneath the sputtering target. These architectural panels typically are produced with a thin film of aluminum thereon.
It has also been suggested that the magnetron may be of the cylindrical, rotary type and be mounted through a side wall of the sputtering chamber. Such a system is disclosed in U.S. Pat. No. 4,356,073, issued Oct. 26, 1982 to Harold E. McKelvey. In the McKelvey disclosure, it can be seen that the cylindrical target is mounted for rotation about a horizontal axis and at one end the target is supported by a pivot pin while the opposite end of the target is supported by an annular seal held within a removable ring, which in turn is sealed to the side wall of the chamber. The interior of the target will be exposed to atmospheric pressure and there also is provided the requisite cooling system and magnet mounting arrangement to provide the magnetic enhancement of the sputtering target. The rotation of the target relative to the magnet will provide a system of utilizing the target to a greater extent than would be possible in those situations where the target was held stationary. One drawback in a system such as this, particularly in a production operation where it might be desirable to change targets only after a day or so of operation, is the necessity to evacuate the chamber each time a new or different target is reintroduced into the sputtering chamber. It should be kept in mind that the normal sputtering chambers are pumped down to vacuum levels in the order of 10.sup.-5 torr. While some targets may be of sufficient thickness that during normal operation they are useable over a period of as long as three weeks, it is not always possible to be assured that a production run will be of sufficient length to utilize the entire useful life of a particular target.
In view of the foregoing, it is an object of the present invention to provide a method and apparatus for switching sputtering targets, of the cylindrical type, without requiring the pumping down of the entire chamber when a target is being replaced by a new or different target.